There are a lot of glues on the market. Any glue has a limited array of substrates it can be used on. Some substrates seem easy to identify (leather, wood), but are actually not (leather usually does not include teflon-treated leather, very common currently) some require more intimate knowledge of the thing you want to glue (PET vs PE).
I do not propose a universal glue, but rather a little stick that accompanies the glue, or can be bought separately for a reasonable price, that is composed of a glue that resembles the main glue in substrate specificity, but is different in the time it needs to set: e.g. instantly, at room temperature. It need not be resistant to water, uv, time, bending, squirrels or any other hardship the main glue has to endure during its life, because it is simply a testing stick. If it sticks to the substrate, the main glue (after its appropriate setting time) will too.
No more waiting for the expensive two component glue to set at a perfect 175°C, to later notice it would have worked, if only the substrate had not contained [insert weird substance].-- loonquawl, Feb 11 2009 I thought this would be a website like www.willitblend.com that's less exciting to watch but more useful.-- marklar, Feb 11 2009 Problem is, though, that it will be hard to make a "quick and cheap" version of the glue that have the same adhesive properties. Only a two-part epoxy is going to behave like a two-part epoxy on all possible surfaces.
Just use nails.-- MaxwellBuchanan, Feb 11 2009 ... so i was carpentering this cross-shaped thingy, handling some supernail, when suddenly ...-- loonquawl, Feb 12 2009 better yet: a radio show-- pashute, Jul 17 2014 As a variant on "contact cement", imagine that for each substrate sold, a particular glue could be sold with it (depending on what customer wants to do with the substrate). The purpose of this glue is NOT to glue the substrate to "anything" else; the purpose is for the glue to stick to the substrate while providing a generic "contact cement" sort of surface.
So, consider two different substrates with two different glues, each providing that generic contact-cement surface. You can then simply clamp the two glue-prepared substrates together, and the two generic contact-cement surfaces bond with each other, guaranteed.
Maybe I'll re-post this as a separate Idea.-- Vernon, Jul 17 2014 It exists - many adhesives either require or can use a primer which adapts the surface to the glue.-- MaxwellBuchanan, Jul 17 2014 random, halfbakery